Thermostat



A. G. STEPHENSON.

THERMOSTAT. APPLICATION HLED JAN.24, I9I9.

1,337,323. Patented Apr. 20,1920.

2 SHEETS-SHEET A. e. STEPHENSON.

THERMOSTAT'. APPLICATION FILED JAN-24, 1919- 1,337,623. Patented A r. 20, 1920. r

V 2 3HEETSSHEET 2.

AXEL Gr. STEPHENSON, OF DENVER, COLORADO.

THERMOSTAT.

I Specification of Letters Patent.

Patented Apr. 20, 1920.

Application filed January 24, 1919. Serial No. 272,932.

To all whom it may concern Be it known that I, AXEL G. STEPHENSON, a citizen of the United States, residing at the city and county of Denver and State of Colorado, have invented certain new and useful Improvements in Thermostats; and I do declare the followin to be a. full, clear, and exact description 0 the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to the characters of reference marked thereon,-which form a part of this specification. Y

My inventionrelates to improvements in thermostats, my object being to provide a construction of this character which shall avoid or overcome some of the difliculties heretofore experienced with instruments of this character. One of these difficulties is that the metal part which vibrates between the two contacts which are utilized to close the circuits for the operation of the motor either for opening or closing the dampers of the stove or furnace, moves so slowly toward either contact that electric arcing results between the vibratory metal part and the electrode which it approaches. This arcing results in corroding the parts, and soon-renders these parts inoperative.

In my improvement, provision is made for a sudden movement of the metal part toward the contact when the'temperature is right for closing the circuit on either the hot or cold side, the metal circuit-closing part moving into engagement with the stationary contact or electrode by gravity.

The movement necessary to close the circuit for thefpurpose of opening or closing the dampers of the stove or furnace as the temperature varies in the room where the thermostat is located is obtained through the medium of a coil spring made of such materials as to make it very sensitive to changes of temperature. I prefer to make this spring of two metals, which expand and contract unequally during changing temperatures, sucn as copper and zinc, there being a layer of copper, for instance, on the inside, and a layer of zinc on the outside, of the coiled. member. In this event, as the temperature rises,.for instance, the zinc will expand to a greater de ree than the copper and cause a movement which will actuate the mechanism between the spring and the electrode on the hot side, to close the circuit,

which will result in closing the front damper, for instance, of the furnace, while, as the temperature falls the spring will be reversely actuated to close the circuit on the cold side with the result that the damper is opened, the opening and closing of. the damper being efi'ectuated through the medium of a motor of ordinary or any suitable construction.

Having briefly outlined my improvement, I will proceed to describe the .same in detail, reference being made to the accompanying drawing in whi h is illustrated an embodiment thereof. In this drawing:

Figure 1 is a View illustrating my improved thermostat in use. i

Fig. 2 is a front. view of the thermostat shown in detail and on a larger scale than Fig. 1.

Fig. 3 is a view of the thermostat shown .on a still larger scale and with the front mostat mechanism with the mechanism shown in a different position from Fig. 3.

Fig. 6 is a fragmentary elevation illustrating the construction for indicating the opening and closing positions of the furnace damper and the corresponding positions of the thermostat mechanism.

Fig. 7 is a section taken on the line 7-7, Fig. 6, the parts being shown on a larger scale.

The same reference characters indicate the same parts in all the views.

Let the numeral 5 designate my improved thermostat considered in its entirety and connected in operative relation with a source of electricity, as a battery 6, the thermostat and battery being suitably connected with a motor, 7, whose operation opens and closes a damper 8 through the medium of a wire or cable, 9, which is connected at one extremity with a crank, 10, of the motor, and at its opposite extremity with the damper 8, the cable engaging a guide pulley, 12, between the motor and the damper. These connections are made by means of a wire or electric conductor. 13, leading from a contact, 1 1, of the thermostat to one pole, 15, of the battery, while a Wire, 16, leads from the opposite pole of the battery to the motor. Two other wires,

', in which the novelty of my invention re 7 sides will now be described.

The structure is mounted upon a relatively stationary support, 21, which will be mounted in a room which the furnace 22 is intendedto warm. Secured to the upper portion of the part 21, which it will be as-.

sumed is composed of wood, is the post or metal contact, 14, from whose inner extremity leads the conductor, 13, as best illustrated in Fig. 4. Around this post is arranged a coil spring 23, composed of several convolutions, the inner extremity of the'spring being secured to the post 14, while'its outer extremity, which I will designate by the numeral 24, is slotted to receive a pin, 25, which is mounted upon the upper extremity of a relatively long lever 26, which is fulcrumed on a rock spindle 27, the latter being pivoted between a metal cross-piece 28. and an angle part 29, mounted on the part 28 and extending outwardly therefrom. This rock spindle passes through the upper extremity of a depending arm 30, the spindle being made fast to the arm, the lower extremity of the latter merging into a transversely arranged segmental member 31, toothed on its lower edge as shown at 32, and engaging a pinion 33, which is journaled on a stationary pin 34, supported on a bracket 35, secured to the stationary base 21. This pinion carries a pin 36, which passes through an opening in the front plate 37 of the thermostat casing, the lower extremity of a hand or pointer 38 being secured to the said pin, whereby, as the pinion is actuated by the horizontal movement of the toothed segment 31, a corresponding movement will be imparted to the hand 38, whose outer extremity is arranged in suitable proximity to a graduated dial 39, formed on the outer surface of the front plate 37. The hand 38 in connection with the dial 39 indicates,through the medium of suitable figures, the temperature of the room, in degrees, where the thermostat is located.

The long lever 26 has a short upper arm 40 and a relatively long lower arm 41, which extends downwardly, as best illustrated in Fig. 4, below the pinion 34, its lower extremity carrying a pin 42, with which are pivotally connected the inner extremities of two pawls, 43 and 44. The outer portion of each of these pawls carries a pin,

.51 and 52, the extremities of the brackets merging into a small plate 53, which is secured to the main plate 54. This plate 54 is provided with two horizontally disposed 5 slots 55, and is slidably connected with the base 21 by two screws 56, passing through these slots, but so arranged that the plate, together with the escapement disks, may be shifted laterally by the movement of a lever 57 fulcrumed on a stationary pin 58, the upper arm of the lever bein'gslotted, as shown at 59, to receive a-pin 60, fast on the plate 54. The lower arm 61 of the lever terminates in a pointer 62, which is arranged in suitable proximity to a graduated dial 63, having figures which indicate temperature in degrees, those shown in the drawings increasing by a common difierence of 10 from 40 to 100. Pivotally mounted on the plate 54, as shown at 64, are two dogs, 65 and 66, adapted to respectively engage the teeth of the disks 47 and 48, to lock these disks against movement in one direction. As shown in the drawing, these dogs act by gravity to maintain their engagement with the teeth of the disks which are so formed that the dogs lock the disks against movement in one direction, but allow them to move freely in the opposite direction, as will be readily understood from an inspection of the drawing, special reference being made to Figs. 3 and 5.

Provision is made for indicating through an opening 67 in the front plate 37 of the instrument, the condition of the furnace damper or draft controlling device 8. This is accomplished through the medium of a slidable plate 68 (see Fig. 7 which is mounted on a vertically slidable arm 69, arranged just inside of the plate 37, the upper portion of the rod being movably retained in a guide-loop, 7 0, mounted on the plate 37, while its lower extremity is con nected as shown at 71, with an arm 72, of a lever 73, fulcrumed on the pin 49 of the toothed disk 47 ,the opposite arm 74 of the lever being slotted as shown at 75, to receive the pin 45, of the pawl 43. the last named pawl is shifted toward the right (referring to Figs. 3, 5 and 6*) far enough to disengage its pin 45 from the toothed edge of the disk 47 and allow'it to drop into engagement with the electrode 49, to close the circuit on the rising temperature When side, the lever 73 is actuated through the medium of the pin 45 of the pawl to raise when the position of the thermostat mech-- anism is reversed and the pawl 44 is shifted to engage the electrode 20 on the falling temperature side of the instrument, the lever 73 is actuated to lower its arm 72 and shift the plate 68 to expose the word Open through the opening 67, as indicated in Fig. 2.

From the foregoing description, the use and operation of my improved device will be readily understood.

If it be assumed that the coil spring 23 has an outside layer of zinc and an inside layer of copper, as the temperature rises the zinc layer will expand to a greater extent than that of the copper and have a tendency to increase the bend or curvature of the convolutions of the spring, and as this bending moment increases, the extremity 24 of the spring will be shifted in the direction indicated by the arrow a (see Fig. 3), and this movement will shift the long lever 26 so that-its arm 40 will move toward the left and its arm 41, toward the right; and assuming that this movement is sufficient, the pawl 43 will be moved to the right to disengage its pin 45 from the teeth of the disk 47 which is held by dog 65, and allow the outer extremity of the pawl to drop into engagement with the electrode 19. By thus allowing the pawl to drop freely, contact is made quickly and arcing is prevented. This movement closes the circuit on the rising temperature side, and through the motor 70, closing the damper 8 of the furnace. This position of the parts of the mechanism is illustrated in Figs. 5 and 6. At the same time that the lever 26 is shifted as just explained, the rock spindle 27 will be actuated to move the toothed segment '31 toward the right, whereby the pinion 34 is actuated to shift the hand 38 from the position shown in Figs. 2 and 3 to that shown in Fig. 5, the hand in this case, in combination with the dial 38, indicating the temperature at which the thermostat is actuated to close the furnace damper. WVhen pawl 43 moves to the right and drops, pawl 44 and pin 46 ride up on disk 48, pin 46 engaging one of the teeth thereof, and dog 66 permitting rotation thereof.

Again, assuming that the temperature of the room lowers to such an extent that its influence on the coil spring 23 is such as to reverse the movement of the spring and throw the lower or long arm of the lever 26 toward the left far enough to disengage the. pin 46 from the teeth of the disk 48, the pawl 44 will drop into engagement with the electrode 20 and close the circuit on the low temperature side of the thermostat, in which event the motor will be actuated to open the damper 8 and the hand 38 will be shifted to occupy a position the reverse of that shown in Fig. 5. The action of pawls and dogs is the reverse of that when moving to the right, as is evident.

It should be explained that as soon as one of the pawls, 43 or 44, engages its electrode, 19 or 20, as the case may be, and the motor 7 -is operated, the operation of the motor at the close of its act breaks the circuit and closes it at the motor on the opposite side, so that it is not necessary for the pawl on the closed side to move quickly away from its electrode, as there is no cur rent in the circuit on that side, as the pawl leaves its electrode. This is an ordinary and well understood condition in apparatus of this kind, and therefore it has not been thought necessary to illustrate the motor construction in the drawing.

It should be further explained that when the lever 57 is shifted so that its lower extremity 62 moves toward the left (see Figs. 2 and 3), the plate 54, together with the mechanism mounted thereon, will be moved bodily toward the right, while the pawls 43 and 44 maintain their same position. The movement of the hand 57 so that its pointer 62 shall travel toward the left, indicates that the circuit will close on the temperature-rising side at a higher degree, since the numbers on the dial 63 increase from right to left. This shifting of the plate 54 toward the right makes it necessary for the pawl 43 to move farther toward the right in order to disengage its pin 45 from the teeth of the disk 47, in order to drop into engagement with the electrode 19. Hence the temperature must rise higher in order to actuate the spring 23 to close the circuit on the temperature-rising side in order to operate the motor to close the damper 8.

Having thus described my invention, what I claim is:

1. A thermostat, comprising a member movable in response to varying temperature conditions, two electrodes, circuits in which the electrodes are respectively located, and means arranged adjacent the electrodes and connected to be actuated by the said member, said means including gravity operable parts releasably mounted to drop quickly into engagement with the respective electrodes to prevent arcing while closing the circuits.

2. A thermostat, comprising a member movable in response to varying temperature conditions, two electrodes. circuits in which said electrodes are respectively located, and means arranged adjacent the electrodes and connected to be operated by the said member, said means including two pawls releasably movable in response to varying temperature conditions, two electrodes, circuits in which the electrodes are respectlvely located, and

means arranged adjacent the electrodes and connected to be actuated by the said member to alternately close the circuits through the electrodes, said means including pivoted gravity operable parts releasably mounted to drop quickly into engagement with the electrodes.

4. A thermostat, including a member movable in response to varying temperature conditions, two electrodes, circuits in which the electrodes are respectively located, and means arranged adjacent the electrodes and connected to be actuated by the said member, said means including two gravity pawls releasably mounted to move quickly into engagement with the respective electrodes to prevent arcing while closing the circuits.

'5. A thermostat, comprising a member -movably responsive to varying temperature conditions, a lever connected to be actuated by said member, twoi circuits, electrodes in the respective circuits and two pawls pivotally connected with the lever and releasably mounted to move quickly into engagement with the'respective electrodes to prevent arcing, while closing the circuits. 7

6. A thermostat, comprising a member movably responsive'to varying temperature conditions, a lever connected to be actuated by said member, two circuits, electrodes in the respective circuits, and two pawls pivotally connected with the lever and toothed rotary disks forming supports for the respective pawls beyond the lever, the pawls being releasabl connected with the disks to allow them to drop into engagement with the respective electrodes.

7. A thermostat, comprising a member movably responsive to varying temperature conditions, a lever connected to be actuated by said member, two circuits, electrodes in the respective circuits, two pawls pivotally connected with the lever, toothed rotary disks forming supports for the respective pawls beyond the lever, the pawls being releasably connected with the 'disks to allow them to dro into engagement with the respective electrodes, and dogs for locking the i disks against rotary movement in one direction.

8. A thermostat, comprising a member movably responsive to varying temperature conditions, a lever connected to be actuated by said member, two circuits,electrodes in the respective circuits, two pawls pivotally connected with the lever, toothed rotary disks forming supports for the respective pawls beyond the lever,the pawls being releasably connected with the disks to allow them to drop into engagement with the respective electrodes, do s for locking the disks against rotary movement in one direction, and temperature-indicating means simultaneously actuated by the lever.

9. A thermostat, comprising a member movably responsive to varying temperature conditions, a lever connected to be actuated by said member, two circuits, electrodes in the respective circuits, two pawls pivotally connected with the lever, toothed rotary disks forming supports for the respective pawls beyond the lever, the pawls being releasably connected with the disks to allow them to drop into engagement with the respective electrodes, dogs for locking the disks against rotary movement in one direction, and temperatureindicating means simultaneously actuated by the lever, said means including a toothedsegment, a meshing pinion, a pointer and a graduated dial, the last named parts being arranged in cooperative relation.

10. A thermostat, comprising a member movably responsive to varying temperature conditions, a lever connected to be actuated by said member, two circuits, electrodes in the respective circuits, two pawls pivotally said plate being laterally shiftable inclependently of the pawls.

11. A thermostat, comprising a member movably responsive to varying temperature conditions, a lever connected to be actuated by said member, two circuits, electrodes in the respective circuits, two pawls pivotally connected with the lever, toothed rotary disks forming supports for the respective pawls beyond the lever, the pawls being releasably connected with the disks to drop into engagement with the respective electrodes, a plate upon which the disks and their dogs are mounted, said plate being laterally shiftable independently of the pawls, and a lever connected in operative relation to shift said plate in either direction.

12. A thermostat, comprising a member movably responsive to varying temperature conditions, a lever connected to be actuated by said member, two circuits, electrodes in the respective circuits, two pawls pivotally connected with the lever, toothed rotary disks forming supports for the respective pawls beyond the lever, the pawls being releasably connected with the disks to drop into engagement with the respective electrodes, a plate upon which the disks and their dogs are mounted, said plate being lat- I erally shiftable independently of the pawls,

and a lever connected in operative relation to shift said plate in either direction, said lever having a pointed extremity and a graduated dial cooperating therewith.

13. A thermostat, comprising a member movably responsive to varying temperature conditions, a lever connected to be actuated by said member, two circuits, electrodes in the respective circuits, two pawls pivotally connected with the lever and releasably mounted to drop into engagement with the respective electrodes to prevent arcing while closing the circuits, and means connected to be actuated by one of the pawls to indicate the openand closed conditions of the dampers controlled by the thermostat.

14. A thermostat, comprising a member movably responsive to varying temperature conditions, a lever connected to be actuated by said member, two circuits, electrodes in the respective circuits, two pawls pivotally connected with the lever and releasably mounted to drop into engagement with the respective electrodes to prevent arcing while closing the circuits, and means connected to be actuated by one of the pawls to indicate the open and closed conditions of the dampers controlled by the thermostat, said means including a lever fulcrumed be tween its extremities and having a plate at one end, the instrument having a front casing plate provided with an opening through which the said indicating plate is visible.

In testimony whereof I afiix m signature.

AXEL G. STEP ENSON. 

